You need to pick the communities based on who is talking about the problem that you're solving, which sounds focused on dev efficiency, so I'd imagine that could be FinOps or EngManagers (maybe?), and then offering advice and your solution when relevant.
Once you find the communities, I've open-sourced a tool you can self-host to handle the relevant post-discovery on Reddit/HN. https://github.com/obris-dev/openmagpie